Mohd Mustafa Al Bakri Abdullah

Fly Ash-based Geopolymer Lightweight Concrete Using Foaming Agent

In this paper, we report the results of our investigation on the possibility of producing foam concrete by using a geopolymer system. Class C fly ash was mixed with an alkaline activator solution (a mixture of sodium silicate and NaOH), and foam was added to the geopolymeric mixture to produce lightweight concrete. The NaOH solution was prepared by dilute NaOH pellets with distilled water. The reactives were mixed to produce a homogeneous mixture, which was placed into a 50 mm mold and cured at two different curing temperatures (60 °C and room temperature), for 24 hours. After the curing process, the strengths of the samples were tested on days 1, 7, and 28. The water absorption, porosity, chemical composition, microstructure, XRD and FTIR analyses were studied. The results showed that the sample which was cured at 60 °C (LW2) produced the maximum compressive strength for all tests, (11.03 MPa, 17.59 MPa, and 18.19 MPa) for days 1, 7, and 28, respectively. Also, the water absorption and porosity of LW2 were reduced by 6.78% and 1.22% after 28 days, respectively. The SEM showed that the LW2 sample had a denser matrix than LW1. This was because LW2 was heat cured, which caused the geopolymerization rate to increase, producing a denser matrix. However for LW1, microcracks were present on the surface, which reduced the compressive strength and increased water absorption and porosity.

Fly ash porous material using geopolymerization process for high temperature exposure.

This paper presents the results of a study on the effect of temperature on geopolymers manufactured using pozzolanic materials (fly ash). In this paper, we report on our investigation of the performance of porous geopolymers made with fly ash after exposure to temperatures from 600 °C up to 1000 °C. The research methodology consisted of pozzolanic materials (fly ash) synthesized with a mixture of sodium hydroxide and sodium silicate solution as an alkaline activator. Foaming agent solution was added to geopolymer paste. The geopolymer paste samples were cured at 60 °C for one day and the geopolymers samples were sintered from 600 °C to 1000 °C to evaluate strength loss due to thermal damage. We also studied their phase formation and microstructure. The heated geopolymers samples were tested by compressive strength after three days. The results showed that the porous geopolymers exhibited strength increases after temperature exposure.

The Relationship of NaOH Molarity, Na2SiO3/NaOH Ratio, Fly Ash/Alkaline Activator Ratio, and Curing Temperature to the Strength of Fly Ash-Based Geopolymer

Geopolymer, produced by the reaction of fly ash with an alkaline activator (mixture of Na2SiO3 and NaOH solutions), is an alternative to the use of ordinary Portland cement (OPC) in the construction industry. However, there are salient parameters that affecting the compressive strength of geopolymer. In this research, the effects of various NaOH molarities, Na2SiO3/NaOH ratios, fly ash/alkaline activator, and curing temperature to the strength of geopolymer paste fly ash were studied. Tests were carried out on 50 x 50 x 50 mm cube geopolymer specimens. Compression tests were conducted on the seventh day of testing for all samples. The test results revealed that a 12 M NaOH solution produced the highest compressive strength for the geopolymer. The combination mass ratios of fly ash/alkaline activator and Na2SiO3/NaOH of 2.0 and 2.5, respectively, produced the highest compressive strength after seven days. Geopolymer samples cured at 60 °C produced compressive strength as high as 70 MPa.

Correlation between Na2SiO3/NaOH Ratio and Fly Ash/Alkaline Activator Ratio to the Strength of Geopolymer

Geopolymer requires an alkaline activator to induce it pozzolanic property and to accelerate the geopolymerisation process. The geopolymerisation process occurs due to the mixing of fly ash, sodium silicate and sodium hydroxide as the alkaline activator, which produces aluminosilicate gel that acts as a binder. As such, the ratios of fly ash to alkaline activator and Na2SiO3/NaOH play an important role in obtaining desirable compressive strength; the concentration of NaOH used in this study was 12 M. Different ratios of fly ash to alkaline activator (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0) and Na2SiO3/NaOH (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0) were investigated in order to determine the maximum compressive strength. The alkaline activator was mixed with fly ash with different ratio as mentioned above and the samples were cured at 70°C for 24 hours and tested on the seventh day. The maximum compressive strength was obtained when the ratios of fly ash to alkaline activator and Na2SiO3/NaOH were 2.0 and 2.5 with compressive strength 73.86 MPa.

Effect of Solids-To-Liquids, Na2SiO3-To-NaOH and Curing Temperature on the Palm Oil Boiler Ash (Si + Ca) Geopolymerisation System

This paper investigates the effect of the solids-to-liquids (S/L) and Na2SiO3/NaOH ratios on the production of palm oil boiler ash (POBA) based geopolymer. Sodium silicate and sodium hydroxide (NaOH) solution were used as alkaline activator with a NaOH concentration of 14 M. The geopolymer samples were prepared with different S/L ratios (0.5, 1.0, 1.25, 1.5, and 1.75) and Na2SiO3/NaOH ratios (0.5, 1.0, 1.5, 2.0, 2.5, and 3.0). The main evaluation techniques in this study were compressive strength, X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscope (SEM). The results showed that the maximum compressive strength (11.9 MPa) was obtained at a S/L ratio and Na2SiO3/NaOH ratio of 1.5 and 2.5 at seven days of testing.

Mechanical properties and wear behavior of brake pads produced from palm slag

Brake pads are important safety devices in vehicles. An effort to avoid the use of asbestos in brake pads has led to the development of asbestos-free brake pads that incorporate various organic and inorganic fillers. Palm slag as a filler in brake pads was investigated in this paper. Different processing pressures were employed during production of samples through compression molding. The properties examined included hardness, compressive strength, and wear behavior. The results showed that brake pad samples prepared with 60 tons of compression pressure resulted in the most desirable properties. Hence, palm slag has its own potential for use as a filler in asbestos-free brake pads.

Thermal Resistance Variations of Fly Ash Geopolymers: Foaming Responses

This paper presents a comparative study of the characteristic of unfoamed and foamed geopolymers after exposure to elevated temperatures (200–800 °C). Unfoamed geopolymers were produced with Class F fly ash and sodium hydroxide and liquid sodium silicate. Porous geopolymers were prepared by foaming with hydrogen peroxide. Unfoamed geopolymers possessed excellent strength of 44.2 MPa and degraded 34% to 15 MPa in foamed geopolymers. The strength of unfoamed geopolymers decreased to 5 MPa with increasing temperature up to 800 °C. Foamed geopolymers behaved differently whereby they deteriorated to 3 MPa at 400 °C and increased up to 11 MPa at 800 °C. Even so, the geopolymers could withstand high temperature without any disintegration and spalling up to 800 °C. The formation of crystalline phases at higher temperature was observed deteriorating the strength of unfoamed geopolymers but enhance the strength of foamed geopolymers. In comparison, foamed geopolymer had better thermal resistance than unfoamed geopolymers as pores provide rooms to counteract the internal damage.

Optimization of Alkaline Activator/Fly ASH Ratio on the Compressive Strength of Manufacturing Fly ASH-BASED Geopolymer

Fly ash and a mixture of alkaline activators namely sodium silicate (Waterglass) and sodium hydroxide (NaOH) solution were used for preparing geopolymer. The aim of this research is to determine the optimum value of the alkaline activator/fly ash ratio. The effect of the oxide molar ratios of SiO2/Al2O3, water content of the alkaline activator and the Waterglass% content were studied for each Alkaline activator/fly ash ratio. The geopolymers were synthesized by the activation of fly ash with alkaline solution at three different alkaline activator/fly ash ratios which were 0.3, 0.35, and 0.4 at a specific constant ratio of waterglass/NaOH solution of 1.00. The geopolymers were cured at 70°C for 24 h and cured to room temperature. Results revealed that the alkaline activator/fly ash ratio of 0.4 has the optimum amount of alkaline liquid, which shows the highest rate of geopolymerization compared to other ratios. A high strength of 8.61 MPa was achieved with 0.4 of activator/fly ash ratio and 14% of waterglass content.

Self-Cleaning Technology in Fabric: A Review

This article gives an overview on photocatalytic self-cleaning technology on fabric resulting from titanium dioxide (TiO2) and zinc oxide (ZnO) as photocatalyst which decompose the organic stain into water and carbon dioxide (CO2) in presence of UV light source. The self-cleaning concept is useful in various application including the textiles materials which are normally used in daily life. This technology also can be developed in other application for instance medical textiles, athletic wear, and military uniform and also outdoor fabrics. Additionally, it is beneficial as it effectively conserves water and improves the appearance of the environment and in long term it will reduce energy, laundry cost and time as well.

The Comparison between Four PLCC Packages and Eight PLCC Packages in Personal Computer (PC) Using Computational Fluid Dynamic (CFD), FLUENT SoftwareTM Using Epoxy Moulding Compound Material (EMC)

The paper present the three dimensional numerical analysis of heat and fluid flow through Plastic Leaded Chip Carrier (PLCC) packages in inline orientation horizontally mounted on a printed circuit board in a wind tunnel is carried out using a commercial CFD code, FLUENTTM by using Epoxy Moulding Compound (EMC) as a main material. The study was made for four and eight packages with different Reynolds Number and package chip powers. The results are presented in term of junction temperature for four and eight PLCC package under different conditions. It is observed the chip temperatures of eight PLCC packages have higher junction temperature compare to four PLCC packages due to effect of other PLCC because of space and gap between PLCC that have more number of PLCC is smaller. Hence it makes junction temperature of eight PLCC higher compare to four PLCC packages. Moreover, the junction temperature of the packages decreases with increase in Reynolds Number.